Apparatus for and a method of saturating non-woven fabrics



June 10, 1969 P. BROWN 3,449,156

APPARATUS FOR AND A METHOD OF SATURATING NON-WOVEN FABRICS Filed July20, 1964 Sheet of 3 /N\/ENTOR PETER BROWN MM l m w,

P. BROWN 3,449,156 APPARATUS FOR AND A METHOD OF SATURATING NON-WOVENFABRICS June 10, 1969 Filed July 20, 1964 Z of5 Sheet IN-VENTOR PETERBROWN MAW/W W June 10, 1969 P. BROWN 3,449,156

APPARATUS FOR AND A METHOD OF SATURATING NON-WOVEN FABRICS Filed July20, 1964 I Sheet ,3 of 3 17 \Z V FIG.7

INVENTOR PETER BROWN United States Patent US. Cl. 117-102 6 ClaimsABSTRACT OF THE DISCLOSURE A method and apparatus for carrying out themethod for impregnating non-woven fibrous stock which comprisesconveying a preformed sheet of non-woven fibrous stock to a bath of abonding agent, passing the sheet through said bath, moving the sheetbetween a nip of a pair of squeeze rollers, at least one of which has aresiliently deformable peripheral layer and projection means made ofmaterial harder than said layer, e.g., a plurality of metallicprojections, said means being so arranged on the peripheral layer thatimproved expression of excess binder and improved release of the stockmaterial are obtained, and subsequently drying the sheet.

This invention relates to apparatus for and a method of impregnatingfibrous webs to form non-woven fabrics and similar non-woven materials.Non-woven fabrics are made without the many processes of spinning andWeaving by bonding fibres together to form a fabric. A fibrous web isgiven substance through the application of a bonding agent. There areseveral methods of applying the bonding agent such as saturation orspraying but this invention is particularly concerned with the mostcommonly used method that of impregnation of a web of fibres with thebonding agent and the subsequent expression of the bonding agent. Suchbonding agents are usually, but not necessarily, aqueous dispersions orlatices of resinous or elastomeric polymers.

Apparatus for the impregnation of webs vary but in general the loose webof fibres is fed on a conveyor until it is sandwiched between twostainless steel screens of woven wire which convey the web through theimpregnation bath. Since impregnated webs are sometimes liable to splitand distort if they are in direct contact with rollers the mesh carriersalso pass through the nip of squeeze rollers between which the webpasses.

The surface covering of the squeeze rollers is of a fairly soft natureto assist expression of excess binder from the impregnated web.

Stainless steel screens have a high initial and replacement cost and thelabour costs involved for maintenance to ensure trouble free productionare also high. Furthermore, wire mesh can distort in use and thus reduceits effective width. It is necessary to remove, clean and replace thescreens from time to time and any dried bonding agent left on thescreens has to be removed for example by burning with the flame from ablow lamp which burning is time consuming.

Moreover, the use of screens can result in insufiicient wetting of thefibres at production speeds and may necessitate the provision of aguiding mechanism so that the screens will not track in directionstransverse to theiir direction of movement.

Moreover the bonding agent is retained in the screen interstices whilepassing through the squeeze rollers with the result that the bestpossible expression is not obtained.

It is an object of the present invention to overcome the abovedisadvantages and dispense wtih screens altogether.

According to the present invention there is provided a squeeze rollerfor use in combination with another roller in the expression of fluidfrom a fibrous material comprising a peripheral layer of a resilientlydeformable material and, on the deformablle material, projections of amaterial which is harder than the deformable material, the arrangementbeing such that the projections will sink into the deformable materialunder pressure at the nip between a pair of rollers.

Preferably the resiliently deformable material is a natural or syntheticrubber and the material which is harder than the deformable material ismetal.

Conveniently the material which is harder than the deformable materialis wire which is wound spirally round the deformable material, althoughthe material could be in the form of a mesh or in the form of a seriesof discrete inserts, such as pegs, studs or discs.

The deformable material may be mounted on a lower substrate which isharder than the deformable material. Furthermore, both the rollers of apair of squeeze rollers may be as above described.

According to another aspect of the present invention there is provided amethod of impregnating fibrous stock comprising the steps of conveying apreformed sheet of fibres to a bath of a bonding agent, passing thesheet through the bonding agent, moving the sheet between the nip of apair of squeeze rollers, at least one of which is as above described andsubsequently drying the sheet.

Preferably the sheet is passed between the nip of at least one pair ofrollers whilst being passed through the bonding agent. This ensureseflicient impregnation, particularly in cases where the sheet iscomparatively thick, although where the sheet is compartively thin mereimmersion of the sheet in the bonding agent is sufi'icient.

However, it is possible to effect impregnation by transfer of thebonding agent from a roller which dips into the bonding agent during itsrotation:

According to yet another aspect of the present invention there isprovided apparatus for impregnating fibrous stock comprising a bathadapted to contain a bonding agent, means for feeding the fibrous stockthrough bonding agent in the bath and to a pair of squeeze rollerspositioned so that the nip between them is above the level of thebonding agent in the bath, at least one squeeze roller being as abovedescribed.

Preferably the means for feeding the fibrous stock through any bondngagent in the bath includes at least one pair of impregnation rollers ofwhich the nip between them is beneath the level of any bonding agent inthe bath.

Conveniently the squeeze rollers comprise a first and second roller andthe impregnation rollers comprise said first roller and a third roller,at least the first roller being of the type above described.

Alternatively the apparatus may comprise two baths adapted to containthe bonding agent and in which the squeeze rollers are positioned so asto depend into any bonding agent within their respective baths and saidmeans for feeding the fibrous stock feeds the stock directly to the nipbetween the squeeze rollers.

In order that the invention may be more clearly understood reference ismade to the accompanying drawings, which illustrate, by way of example,various embodiments thereof and in which:

FIGURE 1 is a side view in section of one embodiment of impregnatingapparatus;

FIGURE 2 is a perspective view of one of the rollers shown in FIGURE 1;

FIGURE 3 is a side view in section of the roller shown in FIGURE 2;

FIGURE 4 is a perspective view of another embodiment of roller;

FIGURE 5 is a side view, partly in section, of yet another embodiment ofroller;

FIGURE 6 is a side view in section of another embodiment of impregnatingapparatus; and

FIGURE 7 is a side view in section of yet another embodiment ofimpregnating apparatus.

Referring to FIGURE 1 an impregnation bath containing a bonding agent 2has immersed therein a first roller 3 having a surface covered with wireas hereinafter described with reference to FIGURES 2 and 3, and alsofour cooperating secondary rollers 4 immersed within the bonding agentand butting the first roller. Also butting the first roller at oppositesides are two rollers, one of which (the feed roller 5) will be sopositioned as to readily receive a sheet or web of fibres and pass itbetween the first roller 3 and the secondary rollers 4, the other (thesqueeze roller 6) will together with the first roller 3 form a pair ofsqueeze rollers.

Referring to FIGURES 2 and 3, the roller 3 comprises a substrate 7carried on a spindle 8. The substrate is rubber of 40 Shore hardness andis covered with a winding of stainless steel wire 9.

Instead of being wound spirally the wire 9 could be woven into a meshand then applied as a covering to the substrate 7. Alternatively therollers, hereinafter described with reference to FIGURE 4 or 5, could beemployed.

The rollers in contact with the first roller 3 may also be covered withwire.

A conveyor may be provided for feeding the web between the first roller3 and the feed roller 5. The squeeze rollers may be relatively movableso that the pressure applied between them may be controlled.

In operation a web of fibres to be impregnated is fed into theimpregnation bath of bonding agent 2 and carried around the first roller3 by means of the secondary rollers 4 in contact with it. The paddingaction obtained in this way ensures rapid Wetting of the web fibres. Theimpregnated web then passes between the nip of the squeeze rollers wherethe pressure will force the wire 9 into the soft substrate 7 of theroller(s). In the nip, therefore, there should be an almost plainsurface which will permit good expression of excess binder. On leavingthe nip the resilient substrate 7 will spring the wire 9 back to itsformer position carrying the fibres with it, thus allowing the web to becarried away for further processing without adhering to the squeezerollers and hence avoiding splitting or distortion.

Referring to FIGURE 4 there is shown another embodiment of roller whichcomprises a soft resilient peripheral substrate 7a and a harder undersubstrate 7b carried on a spindle 8. A number of inserts 10 are held bythe soft resilient substrate 7a and project outwardly therefrom in sucha manner that when pressure is applied to the roller, as in the nipbetween the squeeze rollers 3 and 6 of FIGURE 1, the inserts are forcedinto the substrate 7a. However, in a manner similar to the wire 9 of theroller shown in FIGURES 2 and 3, the inserts spring back to theirinitial positions on leaving the nip.

The inserts can be in the form of studs, pegs or discs.

Referring to FIGURE 5 there is shown another embodiment of roller whichcomprises a series of annular rubber discs 70 which are formed with twocut out portions to receive metal inserts 10a. The discs are displacedat 90 to their adjacent discs and thereby form a roller having fourinserts spaced at ninety degrees to each other for each pair of discs.

Naturally there are a variety of materials which may be used for theresilient substrate and its covering and in selecting them the physicalproperties and dimensions of the materials used and the size of therollers should be considered.

By using as squeeze rollers at least one roller constructed inaccordance with the invention the high expression of excess bondingagent associated with plain rollers is obtained whilst retaining releaseproperties of wire mesh screens.

I have found that this invention provides improved impregnation of theweb of fibres by virtue of the additional padding action within thebonding agent and also since the expression of excess bonding agent isimproved, the web of fibres can be passed through the machine fasterthan hitherto and so increase the rate of production.

Referring to FIGURE 6, there is shown another embodiment of impregnatingapparatus comprising a bath 11 containing a bonding agent 12 .and afirst roller 13 which is partially immersed within the bonding agent. Afeed roller 15 and a squeeze roller 16 also abut the first roller so asto hold the web of fibres or fibrous stock 14 against the first roller13 as the stock passes through the apparatus in the direction of thearrow 17. The relative positions of the first roller 13 and the squeezeroller 16 can be varied to adjust the nip pressure indicated by arrows18. The rollers 13 and 16 are of the kind shown in FIGURES 2 and 3,FIGURE 4 or FIGURE 5.

In operation the fibrous stock 14 is fed over roller 15 until it reachesthe nip between that roller and roller 13. It then follows round roller13, passing through the bonding agent 12 until it reaches the nipbetween the squeeze rollers after which it passes over roller 16 as itis drawn away from the apparatus.

Referring to FIGURE 7, the apparatus therein shown comprises two baths11a and 11b which contain bonding agent 12. Rollers 13a and 13b dependinto their respeetive baths of bonding agent and are relatively movableso that the pressure indicated by arrows 18 at the nip between them canbe varied. The rollers are of the kind shown in FIGURES 2 and 3, FIGURE4 or FIG- URE 5.

In operation the fibrous stock 14 is passed upwardly between the rollers13:: and 13b which themselves pick up sufiicient bonding agent toimpregnate the stock at the nip between them. The impregnated stock isdrawn away from the apparatus in the direction of arrow 17.

The embodiments of impregnating apparatus shown in FIGURES 6 and 7 aresuitable for the impregnation of lightweight fibrous stock. However,with heavier stock it is advantageous to use additional rollers as inthe embodiment shown in FIGURE 1.

Whilst this invention is primarily concerned with the formation ofnon-woven fabrics, the invention might well be useful in the paperindustry.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. A method for impregnating non-woven fibrous stock which comprisesconveying a preformed sheet of nonwoven fibrous stock to a bathcontaining a bonding agent, passing the sheet through the bath, movingthe sheet between a nip of a pair of squeeze rollers, at least one ofwhich has a resiliently deformable peripheral layer and a plurality ofprojections made of material harder than said layer positioned on theperipheral layer, applying a pressure between the squeeze rollers whichcauses the projections to sink into said deformable peripheral layerthereby creating an almost plain surface on the one of said rollers atthe nip between said rollers to effect improved expression of excessbinder from said stock, the projections being of sufficient number toeffect improved release of said fibrous stock upon return to theirinitial positions on said layer, and subsequently drying the impregnatedsheet.

2. The method of claim 1 in which said nip is positioned within saidbath and said projections are made of metal.

3. An apparatus for impregnating fibrous non-woven stock comprising abath containing a bonding agent, means for feeding a non-woven fibrousstock through the bath, a pair of squeeze rollers for receiving thefibrous stock, at least one of said rollers having a resilientlydeformable peripheral layer thereon and a plurality of projections madeof a material harder than said layer positioned on said layer and meansfor receiving the fibrous stock from said squeeze rollers, saidprojections being so arranged on said layer that the pressure betweenthe rollers causes the projections to sink into the deformable layerthereby creating an almost plain surface between said rollers wherebyimproved expression of excess binder is obtained and the projectionsbeing of sufficient number that, upon return to their initial positionson said layer, improved release of the fibrous stock from the layer isobtained.

4. The apparatus of claim 3 in which the nip between two squeeze rollersis arranged within said bath and the projections are made of metal.

5. An apparatus for impregnating non-woven fibrous stock comprising abath containing a bonding agent, a first roller depending in said bath,a resiliently deformable peripheral layer on said roller and a pluralityof metallic projections on said resiliently deformable peripheral layer,a second roller operatively associated with said first roller so thatthe nip therebetween is within said bath, a third roller operativelyassociated with the first roller so that the nip therebetween is outsidethe bath, means for feeding the fibrous stock to the nip between thefirst and second rollers and means for receiving the fibrous stock fromthe nip between the first and third rollers, said metallic projectionsbeing so arranged on said layer that the pressure between said first andsecond rollers causes the projections to sink into said layer therebycreating an almost plain surface on said first roller whereby improvedexpression of excess binder is obtained and the projections being ofsufficient number that upon return to their positions on said layer animproved release of said fibrous stock is obtained.

6. An apparatus for impregnating non woven fibrous stock comprising apair of squeeze rollers, a bonding agent bath associated with each ofsaid squeeze rollers,

each of said squeeze rollers having a resiliently deformable peripherallayer and a plurality of metallic projections on said resilientlydeformable layer, said squeeze rollers being positioned to depend intothe associated baths and contacting each other to form a niptherebetween and means for feeding the fibrous stock to said nip andmeans for receiving the fibrous stock from said nip, the pressureexerted between the squeeze rollers causing the projections thereon tosink into said deformable layers thereby creating substantially plainsurfaces of each of said rollers at the nip whereby improved expressionof excess binder is obtained and the projections being of sufficientnumber that upon return to their positions on said layers, an improvedrelease of said stock is obtained.

References Cited ALFRED L. LEAVITT, Primary Examiner.

CHARLES R. WILSON, Assistant Examiner.

US. Cl. X.R.

